Construction of energy-conserving sucrose utilization pathways for improving poly-γ-glutamic acid production in Bacillus amyloliquefaciens

Abstract

BackgroundSucrose is an naturally abundant and easily fermentable feedstock for various biochemical production processes. By now, several sucrose utilization pathways have been identified and characterized. Among them, the pathway consists of sucrose permease and sucrose phosphorylase is an energy-conserving sucrose utilization pathway because it consumes less ATP when comparing to other known pathways. Bacillus amyloliquefaciens NK-1 strain can use sucrose as the feedstock to produce poly-γ-glutamic acid (γ-PGA), a highly valuable biopolymer. The native sucrose utilization pathway in NK-1 strain consists of phosphoenolpyruvate-dependent phosphotransferase system and sucrose-6-P hydrolase and consumes more ATP than the energy-conserving sucrose utilization pathway.ResultsIn this study, the native sucrose utilization pathway in NK-1 was firstly deleted and generated the B. amyloliquefaciens 3Δ strain. Then four combination of heterologous energy-conserving sucrose utilization pathways were constructed and introduced into the 3Δ strain. Results demonstrated that the combination of cscB (encodes sucrose permease) from Escherichia coli and sucP (encodes sucrose phosphorylase) from Bifidobacterium adolescentis showed the highest sucrose metabolic efficiency. The corresponding mutant consumed 49.4% more sucrose and produced 38.5% more γ-PGA than the NK-1 strain under the same fermentation conditions.ConclusionsTo our best knowledge, this is the first report concerning the enhancement of the target product production by introducing the heterologous energy-conserving sucrose utilization pathways. Such a strategy can be easily extended to other microorganism hosts for reinforced biochemical production using sucrose as substrate.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-017-0712-y) contains supplementary material, which is available to authorized users.

High-level production of poly-γ-glutamic acid from untreated molasses by Bacillus siamensis IR10

“…In this study, gamma radiation was applied to B. siamensis SB1001 to improve its production of γ-PGA in a glucosebased medium. Previous reports have focused on genetic engineering methods to boost γ-PGA production, such as NADPH regeneration in B. licheniformis WX-02 [18], cloning of pgsBCA genes in B. amyloliquefaciens LL3 [27], chromosomal integration of the Vitreoscilla hemoglobin gene (vgb) in B. subtilis [28], and construction of energy-conserving sucrose utilization pathways in B. amyloliquefaciens [12]. This study is the first report that a gamma radiation mutant strain could promote γ-PGA production.…”

“…Most Bacillus strains, including B. subtilis, B. licheniformis, B. amyloliquefaciens, B. methylotrophicus and B. megaterium, have been reported to produce γ-PGA from glucose, glycerol, sucrose, and fructose based media [10][11][12][13][14]. Until now, intensive studies regarding the optimization of the medium composition and fermentation conditions [10,15], metabolic regulation [16,17], and genetic engineering methods [18,19] have been done to improve the yield of γ-PGA.…”

Reversibility of enzymatic reactions might limit biotransformation of organic micropollutants

“…amyloliquefaciens (Feng et al, 2017), we hypothesize that this enzyme could have been involved in the reported reversible phosphorylation of bisphenols. Apart from B.…”

Construction and analysis of an artificial consortium based on the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 to produce the platform chemical 3-hydroxypropionic acid from CO2

“…Moreover, it has been reported that several cyanobacterial species are capable of synthesizing and secreting sucrose as an osmolyte under appropriate environmental stimuli, such as osmotic pressure [3], and this production can be sustained over long time periods and at higher levels than that from plant-based feedstocks such as sugarcane and beet [4,5]. As sucrose is an easily fermentable feedstock for many microorganisms [6,7], significant efforts have been made to improve the production of extracellular sucrose in cyanobacteria [8]. For example, Du et al achieved sucrose productivity at 1.43 mg/L/h in wild-type Synechocystis sp.…”